Steam engine lubricants



' expensive.

essential.

Patented Oct. 21, 1952 UNITED STATES PATENT OFFICE 2,614,991 "STEAMENGINE LUBRICANTS Jones I. Wasson, Union, N. J as'signor to"Standard Oil Development Cmpan'y,"a= corporation of Delaware No D ra'w'ing. 'iApplication Maren 30.1950, S'erialNo. 152,979 1 Claim. (crass-=56) 1 The-present invention relates to steam'cylind'er lubricating oil compositions and related pr'oducts an'd'also to a process of preparing suchcompositions. More specifically, the invention pertains to an oil composition having the properties of hightemperature'stability, relative non-volatility, appropriate emulsification, and other "qualities 'which are desirable for theeifective lubrication ofthe cylinders and valves of locomotives or other steam engines and for other and-related applications and uses.

In the prior art, it has long been considered necessary'to use high-grade ess'entially'paraffinic oils for the'lubrication of the cylinders'and valves of steam engines. These, of-course, are'relatively In addition, in order to "secure -'a desired emulsification of the oil so "as to "coat the wet contacting'surfaces "adequately-it has been'considered necessary to use a substantial quantityof some natural'fatty material such as tallow, or the like. Oils which hav'ea tendency to emulsify with condensed steam are considered They should have a highldegree of stability at temperatures as high as about 750 F. In the prior art, for example, as in the-patent to Lazar, No. 2,084,532, it has been suggested that other materials be used in'lieu of the fat, tallow, or the like, which is-not only costly but tends todecompose at the high operating temperatures. This patent suggests that a small amount of a lime or magnesium soap maybe "added to improve the effectiveness of the mineral oil and to reduce substantially the'requirements for fatty oil. Italso suggests that oils of heavy asphaltic base or of mixed base, suitably refined, may be usedin lieu of'or with-Pennsylvania oil and that residual oils of the Pennsylvania type which contain certain organic acids may be converted by the addition of traces' of oxides (which form soaps) into additive products giving the desired emulsification properties.

'As also indicated in the aforesaid patent,'and as is common knowledge in the prior art, the stability of the steam cylinder oil itself atthe high "operating temperatures involved is an important consideration. In general, unsaturated oils have been considered unsatisfactory and this is another reason that the relatively expensive straight paraflinic oils, especially the Pennsylvania oils, have been preferred.

The present invention is based upon the discovery that by combining certain specific resinous products which may be derived from Pennsylvania oils, with oils of suitable grade derived from non-parafiinic or predominantly non-par- 2 afiinic bases, aniniproved lubricant may be preparedwhich is relatively inexpensive and which is superior in'many respects to anyofthe productsof theprior art. Specifically-it has'been found'that certain'resinous materials, which are 'knownto be precipitated from paraffin base or "from Pennsylvania oils by treatment with propane, may be combined with thenon-p'arafiinic oils of appropriate viscosity'and with a relatively much smaller proportion of tallow than previously used to form an excellent steam cylinder lubricant.

As is well-known in the prior art, paraihnic oils, especially Pennsylvania crude oils, which have their lighter fractions removed, may be dissolved in an excess of liquid propane or other very light hydrocarbons under pressure at ordinary temperatures. The prior art practice is to use at first about two volumes of liquid propane for each volume'of Pennsylvania reduced crude, the solution thereafter being cooled by fully understood.

permitting some of the propane to evaporate.

Suchcoolingmay cause a separation of some of the wax'in "the oil and this wax'maybe removed. Upon addition of further propane up to about 1 0 volu mes per volume of oil and mild heating under pressure, a viscous resinous product of relatively low volatility and high molecular weight is precipitated in the form or a heavy as to plastic solid material having a viscosity in excess of about 1000 S. S. U. at 210 F. This resinous product per se-is well-known in the priorart. 'It is essentially neutral, being substantially'fr'ee from acids, though'its precise composition is not It has been used previously in certain mineral oils of low viscosity (for example, about 150 SpS. U. at F.) as a metal quenchingoil, as'described for instance in the patent to 'Rodman No. '1,818;431. I,

The present invention uses the same resinbu's propane precipitated residue as a modifier for the fnon-parafiinic oil. It should be employed inp roportionsof about '3 or 4 to 12 by weight, ba'sed on the total-composition, in predominantly non-parafiinic oils, for example, a Mid continent oil of about to 300 S. S. U. viscosityat 219 It "It is preferred to add to such'combined ingredients from'about 2 to about 5% of fatty oil, preferably tallow. It will be noted that the principal ingredient is the relatively inexpensive lubricating oil of non-paraffinic base in proportions of 83 to 94% by Weight.

A specific composition which has been found to be very satisfactory consists of about 87% by weight of a Mid-Continent or predominantly nonparafiinic base oil of about 210 S. S. U. viscosity at 210 F., containing about of the. viscous resinous material described above which has a viscosity of over 1,000 S. S. U. at 210 F., and about 3% of tallow or other animal fat. It is emphasized that the resulting product is a high grade steam cylinder oil which has a viscosity of between 4,000 and 5,000 S. S. U. at 100 F. Other inspections are as follows: flash 595 F., viscosity at 210 F. 230 S. S. U., viscosity index 93, Conradson carbon 4.3% and ASTM pour point +25 F.

Another composition which is moderately successful consists of 93 of the oil of non-paraflinic origin, 4% of the viscous propane precipitated resin from Pennsylvania oils and 3% of tallow.

Both of the products just described were tested in large two-cylinder and four-cylinder Baldwin steam locomotives operating at steam pressures of 220 to 235 p. s. i. and steam temperatures of 600 to 700 F., the tractive effort being 63,200 to 115,000 pounds. The locomotives were operated on the lubricants in passenger car Service and also under very severe conditions in freight service in a mountainous region. As controls, a cylinder oil containing 97% of the Mid-Continent oil and 3% of tallow, and a cylinder oil containing 97% of a Pennsylvania oil and 3% of tallow, were also tested. The results of the tests under severe conditions in freight service are shown in the table below:

Steam locomotive tests Lubrication Cylinder Oil Results Mid-0ontinent Oil of 210 S. S. U. at 210 F.:

+13% Tallow Poor, Rods Dry and Bluish.

+3% Tallow +4% Resin Fraction Excellent. +3% Tallow +10% Resin Fraction. Do. Pennsylvania Oil: +3% Tallow Do.

The Mid-Continent oil containing only tallow gave very unsatisfactory results, the cylinder rods being dry and bluish indicating inadequate lubrication. Similar results (not shown in the table) were obtained when the Mid-Continent oil was topped to a viscosity of 300 S. S. U. at 210 F. prior to blending with 3% tallow, showing that increasing the concentration of heavy fractions of Mid- Continent oil in this manner has no beneficial effect. On the other hand, the compositions of this invention containing as little as 4% or as much as 10% of the resin fraction were just as satisfactory as the cylinder oil blend containing the straight Pennsylvania oil, giving excellent lubrication of the locomotive in heavy duty serv-' position) to obtain satisfactory products. Products which perform fairly well may be obtained by combining the resin with the oil, omitting the fatty material altogether. Products containing both the propane extracted resins and also fats, such as tallow, in proportions of 2 to 5%, especially about 3%, give a very superior performance. With such compositions, it is not necessary to use soap of any kind, which is highly advantageous. Soaps leave residues which are frequently objectionable.

While the reasons for superior performance of the composition of this invention are not entirely clear, it is believed that the resins extracted from parafiinic type residual oils form a relatively nonfugitive lubricating film on the relatively moving metal surfaces, even at the high temperatures involved. Since these resinous materials appear to be essentially neutral and are apparently quite fully saturated, they do not harden, form gums, or otherwise build up objectionable deposits to any substantial degree. They thus provide a durable and efiective lubricant film which resists evaporation at the temperatures involved.

It may be noted that high molecular weight polymers, such as acryloids, have been suggested in the past as additives for steam cylinder oils, as in Zimmer and Morway Patent No. 2,330,773. In such cases, however, it was still necessary to employ relatively large amounts of tallow in many cases and furthermore the products seem to have lacked the superior qualities of the high grade essentially paraffinic steam cylinder oils demanded by the trade. On the basis of extensive service tests. the products of this invention are fully equal and in some respects appear to be superior to the straight paraifinic or Pennsylvania stock cylinder lubricants.

Conventional additives may be used, such as anti-oxidants, rust inhibitors, metal deactivators, viscosity index improvers, and the like, where special circumstances make such uses desirable. without departing from the spirit of the invention.

What is claimed is:

An emulsible, soap-free steam cylinder oil composition consisting essentially of about 87% by weight of predominantly Mid-Continent mineral lubricating oil of about to 300 S. S. U. viscosity at 210 F., about 10% of a resinous propane precipitated Pennsylvania type paraffinic petroleum oil residue of substantially higher viscosity, and about 3 of tallow.

JONES I. WASSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

